Radiation imagery chemistry: process – composition – or product th – Imaged product – Including resin or synthetic polymer
Reexamination Certificate
2002-05-31
2004-01-20
Hamilton, Cynthia (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Imaged product
Including resin or synthetic polymer
C430S284100, C430S280100, C430S138000, C522S092000, C528S363000, C528S271000, C528S361000
Reexamination Certificate
active
06680152
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a photosensitive resin composition for use as a material for printed wiring boards. More specifically, it relates to a photosensitive resin composition which is excellent in flexibility and elongation and is also excellent in heat durability and electric characteristics and which is suitable for use as a material for printed wiring boards.
BACKGROUND OF THE INVENTION
In recent years, it is desired to downsize and compact electronic machines and equipment, and it is therefore as well essential to comply with downsizing, a higher fineness and a decrease in weight and thickness with regard to printed wiring boards. A solder resist material to be applied onto a substrate has been generally selected from those materials which are ultraviolet-curable and developable with a diluted alkali and which is excellent in durability against soldering and solvents. However, “build-up” substrates having fine wirings inside recently come to encounter problems in the crack resistance of a cured product of a photosensitive resin since microcracks occur in a solder resist/sealing resin interface in the “build-up” substrates due to a difference between thermal expansion coefficients. Further, it is also demanded to improve a solder resist in insulation reliability between lines of a closely packed wiring.
For improving electric insulation and heat resistance, there has been developed a resin, such as a bismaleimide-triazine resin (BT resin), produced by reacting a cyanate ester compound with an epoxy acrylate. The above resin is improved in both electric characteristics and developability at the same time. However, although the above resin is excellent in electric insulation and heat resistance, it is poor in flexibility and elongation since it has a high elastic modulus due to a hard cyanate ester structure.
Most of conventional methods as a means for improving flexibility and elongation utilize a method in which an elastic modulus as a whole is decreased by incorporating a resin having a low elastic modulus or a method in which a resin having a low elastic modulus is incorporated into a molecule of an unsaturated-group-containing polycarboxylic acid resin by a reaction to achieve a low elastic modulus. Resists obtained according to the above methods have excellent flexibility but have problems of low heat durability and poor electric insulation. There have been developed no resist compositions excellent in flexibility and elongation and also excellent in heat durability and electric insulation.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a photosensitive resin composition having excellent flexibility and excellent elongation and having high heat durability and excellent electric insulation, and a cured product thereof.
According to the present invention, there is provided a photosensitive resin composition (C) containing a photosensitive resin (B) which is a reaction product produced by modifying an epoxy acrylate (a) with a cyanate ester compound (b) to obtain a modification product (A) and reacting the modification product (A) with a polybasic acid anhydride (c), and a compound (d) of the formula,
in which each of n and m is an integer of at least 1.
According to the present invention, further, there is provided a photosensitive resin composition (C) according to the above, which further contains a multistructured (core/shell type) powder (e) having rubber elasticity in a core.
According to the present invention, further, there is provided a cured product of the photosensitive resin composition (C) recited above.
DETAILED DESCRIPTION OF THE INVENTION
The present inventors have made diligent studies to accomplish the above object and as a result have found the following. An epoxy acrylate modified with a cyanate ester compound and a polybasic acid anhydride is used as a main resin for a resist. A compound (d) of the above formula as an essential component is incorporated into a photosensitive resin composition (C), and optionally a multistructured powder (e) having rubber elasticity in a core is further incorporated as an essential component into the photosensitive resin composition (C). In this case, it is possible to impart flexibility to the photosensitive resin composition (C) without impairing other characteristic properties, and there can be obtained a photosensitive resin composition excellent in crack resistance and also excellent in heat durability and electric insulation. On the basis of the above finding, the present invention has been completed.
The epoxy acrylate (a) used in the present invention refers to a reaction product between an epoxy resin and an acrylic acid. Examples of the epoxy acrylate (a) include bisphenol A type epoxy acrylate, bisphenol Z type epoxy acrylate, bisphenol F type epoxy acrylate, biphenol-epoxy acrylate, tetramethylbiphenol-epoxy acrylate, hexamethylbiphenol-epoxy acrylate, xylenenovolak-epoxy acrylate, dicyclopentadienenovolak-epoxy acrylate, phenolnovolak-epoxy acrylate and cresolnovolak-epoxy acrylate. There maybe used a composition and a reaction product containing one compound or at least two compounds of these as required. Of these, easily commercially available bisphenol A type epoxy acrylate is suitable.
The cyanate ester compound (b) used in the present invention is represented by the following formula,
R—(O—CN)
m
in which m is generally an integer of from at least 2 to 5 or less, R is an aromatic organic group, and the cyanate group directly bonds an aromatic ring of the above organic group R.
Specific examples of the cyanate ester compound (b) include 1,3- or 1,4-dicyanatobenzene, 1,3,5-tricyanatobenzene, 1,3-, 1,4-, 1,6-, 1,8-, 2,6- or 2,7-dicyanatonaphthalene, 1,3,6-tricyanatonaphthalene, 4,4′-dicyanatobiphenyl, bis(4-cyanatophenyl)methane, 2,2-bis(4-cyanatophenyl)propane, 2,2-bis(3,5-dibromo-4-cyanatophenyl)propane, bis(4-cyanatophenyl)ether, bis(4-cyanatophenyl)thioether, bis(4-cyanatophenyl)sulfone, tris(4-cyanatophenyl)phosphite, tris(4-cyanatophenyl)phosphate and cyanates obtained by a reaction between novolak and cyan halide.
In addition, there maybe used polyfunctional cyanate ester compounds disclosed in Japanese Patent Publications Nos. 41-1928, 43-18468, 44-4791, 45-11712, 46-1112 and 47-26853 and JP-A-51-63149. These cyanate ester compounds may be used alone or in combination. These components have a remarkably low content level of impurities such as hydrolysable Cl and Na. These components serve to decrease the content of impurities as a whole when incorporated as one component in the present invention, so that the photosensitive resin composition of the present invention is an optimum photosensitive resin composition as a peripheral material for semiconductors.
Further, there may be used a prepolymer having a molecular weight of 200 to 6,000 and having a triazine ring formed by trimerizing cyanato groups of any one of these polyfunctional cyanate ester compounds. The above prepolymer can be obtained by polymerizing the above polyfunctional cyanate ester monomer in the presence of a catalyst selected from acids such as mineral acid and Lewis acid, bases such as sodium alcoholate and tertiary amines, or salts such as sodium carbonate. The prepolymer partially contains unreacted monomer and has the form of a mixture of a monomer and a prepolymer, and the prepolymer in the above form is also suitably used in the present invention.
The polybasic acid anhydride (c) used in the present invention refers to an anhydride having at least two carboxylic acids per molecule. Examples of the polybasic acid anhydride (c) include phthalic acid anhydride, trimellitic acid anhydride, pyromellitic acid anhydride, naphthalene-1,4,5,8-tetracarboxylic acid dianhydride, benzophenone tetracarboxylic acid anhydride, tetrahydropthalic acid anhydride, hexahydrophthalic acid anhydride, 4-methylhexahydropthalic acid anhydride, 3-methylhexahydrophthalic acid anhydride, succinic acid anhydride, dodecenylsuccinic acid anhydride, ethylene glycolbis(anhydrotrimellitate
Ikeguchi Nobuyuki
Ishii Kenji
Ohno Daisuke
Omori Takabumi
Hamilton Cynthia
Mitsubishi Gas Chemical Company Inc.
Wenderoth Lind & Ponack LLP
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